Though commonly misdescribed as such, Vitamin D3 is not an example of a prohormone or a hormone.
Chemical Modification of Silicon Surfaces for Biological Applications.
Chun Wu, Kosei Kawasaki, Yoko Ogawa, Yasukazu Yoshida, Satoru Ohgiya, and Yoshihiro Ohmiya.
In a separate but related system, exocrine tissues secrete their products into ducts and then to the outside of the body or to the intestinal tract.
Classically, endocrine hormones are considered to be derived from amino acids, peptides, or sterols and to act at sites distant from their tissue of origin.
For small molecule hormones, the conversion is often one step, and is often used to regulate hormone levels.
A carbamate group, carbamate ester (e.g., ethyl carbamate), and carbamic acids are functional groups that are inter-related structurally and often are interconverted chemically. Although most of this article concerns organic carbamates, the inorganic salt ammonium carbamate is produced on a large scale as an intermediate in the production of the commodity chemical urea from ammonia and carbon dioxide.
In addition, systemic feedback mechanisms have evolved to regulate the production of endocrine hormones.
Once a hormone is secreted by an endocrine tissue, it generally binds to a specific plasma protein carrier, with the complex being disseminated to distant tissues.
Hormones are normally present in the plasma and interstitial tissue at concentrations in the range of 10M.